3. Hormones can stimulate the same cell type or can affect distant cells as well.

What do hormones alter?

They coordinate cellular activities of tissues in distant portions of the body.

Alter operations of genes, existing proteins (and the rate of synthesis of proteins (by changing the rate of transcription and translation)

Turn an existing enzyme or membrane channels "on" or "off" by changing its shape or structure.

If hormones travel all over the body, can they activate the wrong cell type?

Even though all cells get exposed to said hormone they may not have the functional (necessary) receptor.

How can hormones affect tissues?

Hormones can modify the physical structure or biochemical properties of its target cells. This target cells can be affected by one hormone, Slowly altering the cells metabolic functions, then the tissues and finally the organs.

Direct communication

transmission: Through gap junctions

Chemical mediators: Ions, small solutes, lipid soluble materials

Distribution of effects: Usually limited to adjacent cells of the same type that are interconnected by connexons.

Paracrine communication

Transmission: Through extracellular fluid

Chemical Mediators: Paracrine factors

Distribution of effects: Primarily limited to local area, where concentrations are relatively high. Target cells must have appropriate receptors.

Endocrine communication

Transmission: Through the circulatory system

Chemical Mediators: Hormones

Distribution of effects: Target cells are primarily in other tissues and organs and must have appropriate receptors.

Synaptic communication

Transmission: Across synaptic clefts

Chemical Mediators: Neurotransmitters

Distribution of effects: Limited to very specific area. Target cells must have appropriate receptors.

What type of molecule is a hormone

Steroid or amino acid-based

Master endocrine gland that regulates other endocrine organs

Anterior pituitary

How are hormones regulated

Negative feedback

Factors

Have no set chemical structure

As the glucose levels decrease _____ is released by the _______ so cells can take up glucose.